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LibJS: Implement WeakRef changes from 'Symbol as WeakMap Keys Proposal'

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This commit is contained in:
Idan Horowitz 2022-06-22 23:09:59 +03:00
parent dbd0110721
commit 53ed8decaf
6 changed files with 69 additions and 26 deletions
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34
Userland/Libraries/LibJS/Runtime/WeakRef.cpp
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@ -1,5 +1,5 @@
/*
* Copyright (c) 2021, Idan Horowitz <idan.horowitz@serenityos.org>
* Copyright (c) 2021-2022, Idan Horowitz <idan.horowitz@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
@ -8,26 +8,38 @@
namespace JS {
WeakRef* WeakRef::create(GlobalObject& global_object, Object* object)
WeakRef* WeakRef::create(GlobalObject& global_object, Object& value)
{
return global_object.heap().allocate<WeakRef>(global_object, object, *global_object.weak_ref_prototype());
return global_object.heap().allocate<WeakRef>(global_object, value, *global_object.weak_ref_prototype());
}
WeakRef::WeakRef(Object* object, Object& prototype)
WeakRef* WeakRef::create(GlobalObject& global_object, Symbol& value)
{
return global_object.heap().allocate<WeakRef>(global_object, value, *global_object.weak_ref_prototype());
}
WeakRef::WeakRef(Object& value, Object& prototype)
: Object(prototype)
, WeakContainer(heap())
, m_value(object)
, m_value(&value)
, m_last_execution_generation(vm().execution_generation())
{
}
WeakRef::WeakRef(Symbol& value, Object& prototype)
: Object(prototype)
, WeakContainer(heap())
, m_value(&value)
, m_last_execution_generation(vm().execution_generation())
{
}
void WeakRef::remove_dead_cells(Badge<Heap>)
{
VERIFY(m_value);
if (m_value->state() == Cell::State::Live)
if (m_value.visit([](Cell* cell) -> bool { return cell->state() == Cell::State::Live; }, [](Empty) -> bool { VERIFY_NOT_REACHED(); }))
return;
m_value = nullptr;
m_value = Empty {};
// This is an optimization, we deregister from the garbage collector early (even if we were not garbage collected ourself yet)
// to reduce the garbage collection overhead, which we can do because a cleared weak ref cannot be reused.
WeakContainer::deregister();
@ -37,8 +49,10 @@ void WeakRef::visit_edges(Visitor& visitor)
{
Base::visit_edges(visitor);
if (vm().execution_generation() == m_last_execution_generation)
visitor.visit(m_value);
if (vm().execution_generation() == m_last_execution_generation) {
auto* cell = m_value.visit([](Cell* cell) -> Cell* { return cell; }, [](Empty) -> Cell* { return nullptr; });
visitor.visit(cell);
}
}
}